[TD-10645][raft]<feature>add raft append message handle

source/libs/sync/inc/raft_configuration.h

@@ -20,7 +20,7 @@
 #include "sync_type.h"
 
 // return -1 if cannot find this id
-int syncRaftConfigurationIndexOfVoter(SSyncRaft *pRaft, SyncNodeId id);
+int syncRaftConfigurationIndexOfNode(SSyncRaft *pRaft, SyncNodeId id);
 
 int syncRaftConfigurationVoterCount(SSyncRaft *pRaft);
 

source/libs/sync/inc/raft_log.h

@@ -37,6 +37,8 @@ SSyncRaftLog* syncRaftLogOpen();
 
 SyncIndex syncRaftLogLastIndex(SSyncRaftLog* pLog);
 
+SyncIndex syncRaftLogSnapshotIndex(SSyncRaftLog* pLog);
+
 SyncTerm syncRaftLogLastTerm(SSyncRaftLog* pLog);
 
 bool syncRaftLogIsUptodate(SSyncRaftLog* pLog, SyncIndex index, SyncTerm term);
@@ -50,4 +52,13 @@ SyncTerm syncRaftLogTermOf(SSyncRaftLog* pLog, SyncIndex index);
 int syncRaftLogAcquire(SSyncRaftLog* pLog, SyncIndex index, int maxMsgSize,
                       SSyncRaftEntry **ppEntries, int *n);
 
+void syncRaftLogRelease(SSyncRaftLog* pLog, SyncIndex index,
+                      SSyncRaftEntry *pEntries, int n);
+
+bool syncRaftLogMatchTerm();
+
+static FORCE_INLINE bool syncRaftLogIsCommitted(SSyncRaftLog* pLog, SyncIndex index) {
+  return pLog->commitIndex > index;
+}
+
 #endif  /* _TD_LIBS_SYNC_RAFT_LOG_H */

source/libs/sync/inc/raft_message.h

@@ -65,10 +65,10 @@ typedef struct RaftMsg_VoteResp {
 
 typedef struct RaftMsg_Append_Entries {
   // index of log entry preceeding new ones
-  SyncIndex prevIndex;
+  SyncIndex index;
 
   // term of entry at prevIndex
-  SyncTerm prevTerm;
+  SyncTerm term;
 
   // leader's commit index.
   SyncIndex commitIndex;
@@ -80,6 +80,10 @@ typedef struct RaftMsg_Append_Entries {
   SSyncRaftEntry* entries;
 } RaftMsg_Append_Entries;
 
+typedef struct RaftMsg_Append_Resp {
+  SyncIndex index;
+} RaftMsg_Append_Resp;
+
 typedef struct SSyncMessage {
   RaftMessageType msgType;
   SyncTerm term;
@@ -95,6 +99,7 @@ typedef struct SSyncMessage {
     RaftMsg_VoteResp voteResp;
 
     RaftMsg_Append_Entries appendEntries;
+    RaftMsg_Append_Resp appendResp;
   };
 } SSyncMessage;
 
@@ -167,7 +172,7 @@ static FORCE_INLINE SSyncMessage* syncNewVoteRespMsg(SyncGroupId groupId, SyncNo
 }
 
 static FORCE_INLINE SSyncMessage* syncNewAppendMsg(SyncGroupId groupId, SyncNodeId from,
-                                                  SyncTerm term, SyncIndex prevIndex, SyncTerm prevTerm,
+                                                  SyncTerm term, SyncIndex logIndex, SyncTerm logTerm,
                                                   SyncIndex commitIndex, int nEntries, SSyncRaftEntry* entries) {
   SSyncMessage* pMsg = (SSyncMessage*)malloc(sizeof(SSyncMessage));
   if (pMsg == NULL) {
@@ -179,8 +184,8 @@ static FORCE_INLINE SSyncMessage* syncNewAppendMsg(SyncGroupId groupId, SyncNode
     .term = term,
     .msgType = RAFT_MSG_APPEND,
     .appendEntries = (RaftMsg_Append_Entries) {
-      .prevIndex = prevIndex,
-      .prevTerm = prevTerm,
+      .index = logIndex,
+      .term = logTerm,
       .commitIndex = commitIndex,
       .nEntries = nEntries,
       .entries = entries,
@@ -190,6 +195,24 @@ static FORCE_INLINE SSyncMessage* syncNewAppendMsg(SyncGroupId groupId, SyncNode
   return pMsg;
 }
 
+static FORCE_INLINE SSyncMessage* syncNewEmptyAppendRespMsg(SyncGroupId groupId, SyncNodeId from, SyncTerm term) {
+  SSyncMessage* pMsg = (SSyncMessage*)malloc(sizeof(SSyncMessage));
+  if (pMsg == NULL) {
+    return NULL;
+  }
+  *pMsg = (SSyncMessage) {
+    .groupId = groupId,
+    .from = from,
+    .term = term,
+    .msgType = RAFT_MSG_APPEND_RESP,
+    .appendResp = (RaftMsg_Append_Resp) {
+
+    },
+  };
+
+  return pMsg;
+}
+
 static FORCE_INLINE bool syncIsInternalMsg(RaftMessageType msgType) {
   return msgType == RAFT_MSG_INTERNAL_PROP ||
          msgType == RAFT_MSG_INTERNAL_ELECTION;
@@ -209,5 +232,6 @@ void syncFreeMessage(const SSyncMessage* pMsg);
 int syncRaftHandleElectionMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg);
 int syncRaftHandleVoteMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg);
 int syncRaftHandleVoteRespMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg);
+int syncRaftHandleAppendEntriesMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg);
 
 #endif  /* _TD_LIBS_SYNC_RAFT_MESSAGE_H */
\ No newline at end of file

source/libs/sync/src/raft.c

@@ -16,6 +16,7 @@
 #include "raft.h"
 #include "raft_configuration.h"
 #include "raft_log.h"
+#include "raft_replication.h"
 #include "syncInt.h"
 
 #define RAFT_READ_LOG_MAX_NUM 100
@@ -215,7 +216,7 @@ int syncRaftNumOfGranted(SSyncRaft* pRaft, SyncNodeId id, bool preVote, bool acc
       pRaft->selfGroupId, pRaft->selfId, id, pRaft->term);
   }
   
-  int voteIndex = syncRaftConfigurationIndexOfVoter(pRaft, id);
+  int voteIndex = syncRaftConfigurationIndexOfNode(pRaft, id);
   assert(voteIndex < pRaft->cluster.replica && voteIndex >= 0);
   assert(pRaft->candidateState.votes[voteIndex] == SYNC_RAFT_VOTE_RESP_UNKNOWN);
 
@@ -279,8 +280,38 @@ static bool preHandleNewTermMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg)
 }
 
 static bool preHandleOldTermMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg) {
-  // TODO
-  // if receive old term message, no need to continue
+  if (pRaft->checkQuorum && pMsg->msgType == RAFT_MSG_APPEND) {
+		/**
+     * We have received messages from a leader at a lower term. It is possible
+		 * that these messages were simply delayed in the network, but this could
+		 * also mean that this node has advanced its term number during a network
+		 * partition, and it is now unable to either win an election or to rejoin
+	   * the majority on the old term. If checkQuorum is false, this will be
+		 * handled by incrementing term numbers in response to MsgVote with a
+		 * higher term, but if checkQuorum is true we may not advance the term on
+		 * MsgVote and must generate other messages to advance the term. The net
+		 * result of these two features is to minimize the disruption caused by
+		 * nodes that have been removed from the cluster's configuration: a
+		 * removed node will send MsgVotes (or MsgPreVotes) which will be ignored,
+		 * but it will not receive MsgApp or MsgHeartbeat, so it will not create
+		 * disruptive term increases
+    **/
+    int peerIndex = syncRaftConfigurationIndexOfNode(pRaft, pMsg->from);
+    if (peerIndex < 0) {
+      return true;
+    }
+    SSyncMessage* msg = syncNewEmptyAppendRespMsg(pRaft->selfGroupId, pRaft->selfId, pRaft->term);
+    if (msg == NULL) {
+      return true;
+    }
+
+    pRaft->io.send(msg, &(pRaft->cluster.nodeInfo[peerIndex]));
+  } else {
+    // ignore other cases
+    syncInfo("[%d:%d] [term:%" PRId64 "] ignored a %d message with lower term from %d [term:%" PRId64 "]",
+      pRaft->selfGroupId, pRaft->selfId, pRaft->term, pMsg->msgType, pMsg->from, pMsg->term);    
+  }
+
   return true;
 }
 
@@ -308,6 +339,9 @@ static int stepCandidate(SSyncRaft* pRaft, const SSyncMessage* pMsg) {
   if (msgType == RAFT_MSG_VOTE_RESP) {
     syncRaftHandleVoteRespMessage(pRaft, pMsg);
     return 0;
+  } else if (msgType == RAFT_MSG_APPEND) {
+    syncRaftBecomeFollower(pRaft, pRaft->term, pMsg->from);
+    syncRaftHandleAppendEntriesMessage(pRaft, pMsg);
   }
   return 0;
 }
@@ -353,7 +387,7 @@ static int triggerAll(SSyncRaft* pRaft) {
       continue;
     }
 
-    
+    syncRaftReplicate(pRaft, i);
   }
 }
 

source/libs/sync/src/raft_configuration.c

@@ -16,7 +16,7 @@
 #include "raft_configuration.h"
 #include "raft.h"
 
-int syncRaftConfigurationIndexOfVoter(SSyncRaft *pRaft, SyncNodeId id) {
+int syncRaftConfigurationIndexOfNode(SSyncRaft *pRaft, SyncNodeId id) {
   return (int)(id);
 }
 

source/libs/sync/src/raft_handle_append_entries_message.c

+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <cli@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "syncInt.h"
+#include "raft.h"
+#include "raft_log.h"
+#include "raft_configuration.h"
+#include "raft_message.h"
+
+int syncRaftHandleAppendEntriesMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg) {
+  RaftMsg_Append_Entries *appendEntries = &(pMsg->appendEntries);
+  
+  int peerIndex = syncRaftConfigurationIndexOfNode(pRaft, pMsg->from);
+  
+  if (peerIndex < 0) {
+    return 0;
+  }
+
+  SSyncMessage* pRespMsg = syncNewEmptyAppendRespMsg(pRaft->selfGroupId, pRaft->selfId, pRaft->term);
+  if (pRespMsg == NULL) {
+    return 0;
+  }
+
+  RaftMsg_Append_Entries *appendResp = &(pMsg->appendResp);
+  // ignore committed logs
+  if (syncRaftLogIsCommitted(pRaft->log, appendEntries->index)) {
+    appendResp->index = pRaft->log->commitIndex;
+    goto out;
+  }
+
+  syncInfo("[%d:%d] recv append from %d index %" PRId64"",
+      pRaft->selfGroupId, pRaft->selfId, pMsg->from, appendEntries->index); 
+
+out:
+  pRaft->io.send(pRespMsg, &(pRaft->cluster.nodeInfo[peerIndex]));
+  return 0;
+}
\ No newline at end of file

source/libs/sync/src/raft_handle_vote_message.c

@@ -23,7 +23,7 @@ static bool canGrantVoteMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg);
 
 int syncRaftHandleVoteMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg) {
   SSyncMessage* pRespMsg;
-  int voteIndex = syncRaftConfigurationIndexOfVoter(pRaft, pMsg->from);
+  int voteIndex = syncRaftConfigurationIndexOfNode(pRaft, pMsg->from);
   if (voteIndex == -1) {
     return 0;
   }

source/libs/sync/src/raft_handle_vote_resp_message.c

@@ -23,7 +23,7 @@ int syncRaftHandleVoteRespMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg) {
   int quorum;
   int voterIndex;
 
-  voterIndex = syncRaftConfigurationIndexOfVoter(pRaft, pMsg->from);
+  voterIndex = syncRaftConfigurationIndexOfNode(pRaft, pMsg->from);
   if (voterIndex == -1) {
     syncError("[%d:%d] recv vote resp from unknown server %d", pRaft->selfGroupId, pRaft->selfId, pMsg->from);
     return 0;

source/libs/sync/src/raft_log.c

@@ -23,6 +23,10 @@ SyncIndex syncRaftLogLastIndex(SSyncRaftLog* pLog) {
   return 0;
 }
 
+SyncIndex syncRaftLogSnapshotIndex(SSyncRaftLog* pLog) {
+  return 0;
+}
+
 SyncTerm syncRaftLogLastTerm(SSyncRaftLog* pLog) {
   return 0;
 }
@@ -46,4 +50,9 @@ SyncTerm syncRaftLogTermOf(SSyncRaftLog* pLog, SyncIndex index) {
 int syncRaftLogAcquire(SSyncRaftLog* pLog, SyncIndex index, int maxMsgSize,
                       SSyncRaftEntry **ppEntries, int *n) {
   return 0;
+}
+
+void syncRaftLogRelease(SSyncRaftLog* pLog, SyncIndex index,
+                      SSyncRaftEntry *pEntries, int n) {
+  return;
 }
\ No newline at end of file

source/libs/sync/src/raft_replication.c

@@ -33,13 +33,62 @@ int syncRaftReplicate(SSyncRaft* pRaft, int i) {
   }
 
   SyncIndex nextIndex = syncRaftProgressNextIndex(progress);
-  SyncIndex prevIndex = nextIndex - 1;
-  SyncTerm prevTerm = syncRaftLogTermOf(pRaft->log, prevIndex);
+  SyncIndex snapshotIndex = syncRaftLogSnapshotIndex(pRaft->log);
+  bool inSnapshot = syncRaftProgressInSnapshot(progress);
+  SyncIndex prevIndex;
+  SyncTerm prevTerm;
+
+  /**
+   * From Section 3.5:
+   *
+   *   When sending an AppendEntries RPC, the leader includes the index and
+   *   term of the entry in its log that immediately precedes the new
+   *   entries. If the follower does not find an entry in its log with the
+   *   same index and term, then it refuses the new entries. The consistency
+   *   check acts as an induction step: the initial empty state of the logs
+   *   satisfies the Log Matching Property, and the consistency check
+   *   preserves the Log Matching Property whenever logs are extended. As a
+   *   result, whenever AppendEntries returns successfully, the leader knows
+   *   that the follower's log is identical to its own log up through the new
+   *   entries (Log Matching Property in Figure 3.2).
+   **/
+  if (nextIndex == 1) {
+    /**
+     * We're including the very first entry, so prevIndex and prevTerm are
+     * null. If the first entry is not available anymore, send the last
+     * snapshot if we're not already sending one. 
+     **/
+    if (snapshotIndex > 0 && !inSnapshot) {
+      goto send_snapshot;
+    }
+
+    // otherwise send append entries from start
+    prevIndex = 0;
+    prevTerm = 0;    
+  } else {
+    /**
+     * Set prevIndex and prevTerm to the index and term of the entry at
+     * nextIndex - 1. 
+     **/ 
+    prevIndex = nextIndex - 1;
+    prevTerm = syncRaftLogTermOf(pRaft->log, prevIndex);
+    /**
+     * If the entry is not anymore in our log, send the last snapshot if we're
+     * not doing so already.
+     **/
+    if (prevTerm == SYNC_NON_TERM && !inSnapshot) {
+      goto send_snapshot;
+    }
+  }
 
-  if (prevTerm == SYNC_NON_TERM && !syncRaftProgressInSnapshot(progress)) {
-    goto send_snapshot;
+  /* Send empty AppendEntries RPC when installing a snaphot */
+  if (inSnapshot) {
+    prevIndex = syncRaftLogLastIndex(pRaft->log);
+    prevTerm = syncRaftLogLastTerm(pRaft->log);
   }
 
+  return sendAppendEntries(pRaft, i, prevIndex, prevTerm);
+
 send_snapshot:
   if (syncRaftProgressRecentActive(progress)) {
     /* Only send a snapshot when we have heard from the server */
@@ -69,7 +118,7 @@ static int sendAppendEntries(SSyncRaft* pRaft, int i, SyncIndex prevIndex, SyncT
                                       nEntry, entries);
 
   if (msg == NULL) {
-    return 0;
+    goto err_release_log;
   }
 
   pRaft->io.send(msg, pNode);
@@ -87,4 +136,8 @@ static int sendAppendEntries(SSyncRaft* pRaft, int i, SyncIndex prevIndex, SyncT
   syncRaftProgressUpdateSendTick(progress, pRaft->currentTick);
 
   return 0;
+
+err_release_log:
+  syncRaftLogRelease(pRaft->log, nextIndex, entries, nEntry);
+  return 0;
 }
\ No newline at end of file